Centrifugal casting process and apparatus



June 2, 1964 s. A. CORTRIGHT ET AL 3,135,593

CENTRIFUGAL CASTING PROCESS AND APPARATUS Filed April 26, 1960 2 Sheets-Sheet 1 INVENTORS 5 TA NLE Y4. ('URT/P/Gl/T AND ism/ms flow/r7 June 2, 6 s. A. CORTRIGHT ET AL 3, 5

CENTRIFUGAL CASTING PROCESS AND APPARATUS Filed April 26, 1960 2 Sheets-Sheet 2 AUG:

INVENTORS 5m 01.5) 4. (bEI'R/G/Vf 44/0 72mm flow/r7 Jk.

6/ /2 0 27' r 0 EN Y United States Patent 3,135,593 CENTRIFUGAL CASTING PROCESS AND APPARATUS Stanley A. Cortright and Thomas Hewitt, Jr., Corning,

N.Y., assignors to Corning Glass Works, Corning, N.Y.,

a corporation of New York Filed Apr. 26, 1960, Ser. No. 24,838 Claims. (Cl. 65-71) The present invention relates to the centrifugal casting of large articles from low viscosity molten material, such as glass or the like. Certain articles, such as radomes for example, to be usable must be substantially wholly free from imperfections. To produce such articles great care must accordingly be exercised to initially obtain a molten material of a suitable quality; and the method of feeding such material to the mold and its ultimate formation into the article must be accomplished in such a fashion as to avoid the introduction of air pockets or striations in the article wall.

It has heretofore been found that low viscosity molten material may be stream fed to molds arranged for rotation in either a horizontal plane, or in an inclined plane and centrifuged into a hollow article. However, the quality of the resulting article has been found inferior to that desired for radomes and the like.

According to the present invention a high quality ogiveshaped product is obtained by directing a low viscosity glass stream of small cross section initially into the axial center of a mold arranged below it, rotatable in a horizontal plane. After filling the nosev of the mold cavity, the mold is moved sideways to keep the stream impinging adjacent to the mold wall along its line of juncture with the pool therein, thus adding to the volume of molten glass within the pool while avoiding its disturbance to the extent that blisters might be introduced into the accumulation of molten glass. Termination of lateral travel of the mold is calculated to substantially coincide with the discontinuance of feeding and the commencement of centrifuging the accumulated glass. To assure proper commencement of feeding, the free end of the stream of material is pinched off between a pair of shear blades arranged in the same horizontal plane and which are butted against one another at the stream axis to perform the pinch-off operation so as to avoid lateral displacement of the downcoming stream by a shear blade, as would occur were conventional shear blades, which pass one another in overlapping relation, employed. The so pinched-off end of the stream is quickly moved out of the path of the oncoming stream and discarded. A similar severing operation is subsequently performed by the shear blades to terminate feeding in a manner to avoid lateral displacement of the trailing end of the severed stream and the oncoming stream then diverted from entering the mold.

For a better understanding of the invention, reference will hereinafter be made to the accompanying drawings wherein FIG. 1 is a diagrammatic illustration of a preferred form of apparatus embodying the invention ar ranged in association with a forehearth for feeding a stream of glass thereto; FIG. 2 is a wiring diagram of such apparatus; and FIGS. 3 to 5 diagrammatically illustrate the relationship of the stream and mold during dif ferent stages of mold charging.

Referring to the drawings in detail, 11 represents a portion of the forehearth from which a glass stream 12 is issuing through a suitable bottom outlet 13.

Arranged just below and on two opposite sides of the outlet 13 are shear blades 14 and 15 carried on the free ends of the piston shafts of pneumatic cylinders 16 and 17, respectively, and held in their retracted positions by springs 18 and 19 arranged within such cylinders. As will be observed, blades 14 and 15 are in the same hori- Patented June 2, 1964 zontal plane and thus are adapted for shearing a stream by being brought into abutting relation in the midst of the stream. As can be seen from FIG. 2, a magnetic valve 20 is arranged to feed air to the outer ends of cylinders 16 and 17 to effect a shearing or pinching off of glass from the parent stream 12 whenever its associated winding 24 is energized.

Also below and to one side of outlet 13 there is a chute 30 carried on the free end of the piston shaft of a pneumatic cylinder 31 and adapted to be projected into and out of the path of stream 12 by such cylinder. As can be seen in FIG. 2, air is supplied to cylinder 31 through a suitable distributing valve 32 having suitable windings 106 and 107 for operating it to selectively feed operating air to cylinder 31 through a conduit 33 or 34.

centrifuging apparatus embodying the invention is arranged on a carriage 40 having embodied within it a suitable mold rotating motor 41 on whose shaft is mounted a mold 42. As schematically illustrated in FIG. 2 the motor is operable at high or low speed under control of a suitable timing mechanism operable by a motor 45, as will be more fully described later.

The carriage 40 is adapted to be moved, between the full and interrupted line position shown, over a track 46 by a hydraulic cylinder 50 to the piston shaft 150 of which the carriage is attached. Operating fluid for cylinder 59 is supplied to it through conduits 51 and 52 extending between it and a conventional servo valve 55 of known manufacture and to which suitable fluid supply and return lines 56 and 57, respectively, are connected. The valve 55 is carried on a panel 69 attached to track 46 and is operable by a pivoted arm 61 under the influence of springs 62 and 63, a solenoid 67 and by a cam 65 arranged on a shaft 66 driven by a motor 70 mounted upon a carriage carried bracket 71. Motor 70 is so controlled that it rotates cam 65 180 during a feeding cycle. The contour of the cam is such that it so controls or programs the rate of travel of the carriage 40, through the medium of the servo valve 55, as to maintain the stream 12 directed within the pool adjacent the mold cavity wall at its line of juncture with the top level of the pool therein through the completion of a feeding cycle. With cam 65 in the position shown by interrupted lines the arm 61 is maintained in a position to maintain the passages of valve 55 closed. A relay 89 (FIG. 2) is operable, over an obvious circuit, upon closure of contacts 92 by a push button 93 to at its contacts 90 complete a locking circuit for itself and at its contacts 88 complete an operating circuit for solenoid 67. The solenoid 67 operating circuit extends from a current source terminal X, through cam contacts 85 of a cam 86 arranged on a cam drive shaft 74, a conductor 87, through the winding of the solenoid and contacts 38 of relay 89 to a Y terminal of the current source.

With solenoid 67 energized the effect of spring 62 is overcome and permits arm 61 to move in a direction to permit valve 55 to feed fluid through conduit 51 and the rightward end of cylinder 50 to move the carriage 40 leftward and bring mold 42 to its loading position. In such position the cam 65 restores arm 61 to its original position in which it is shown. This places the initial portion of the return movement of the mold 42 under control of cam 65. The operating circuit of the cam drive motor '70 is shown in FIG. 2 and extends from an X terminal of a suitable current source, through break contacts 72 of a cam 73 driven by motor 76 through cam shaft 74, the make contacts 75 of a relay 76 and a conductor 77 through motor 70 to a Y terminal of the same current source. The relay 76 for completing the above traced circuit has an operating circuit extending from an X terminal through contacts 80, momentarily closeable by a cam 4 carried on the shaft 81 of a feeder timer driven by a motor 82, conductor 77, the winding of such relay and a Y terminal of the current source. A locking circuit for relay 76 extends through its contacts 75 and the break contacts 72 of cam 73 on shaft 74. An operating circuit is provided for motor 82 and an associated relay 102, through contacts 101 of a push button 100. An alternative circuit for motor 82 and a locking for relay 102 is closed by its contacts 103 via contacts 164 of a feeder timer cam 7 The sequence of operations that occur during a feeding cycle are primarily under control of cams 1 through 7 carried by timer shaft 81, a spinner timer shaft 95 driven by motor 45, the cams driven by shaft 74- and circuitry associated therewith.

In order to illustrate the relationship between the stream of glass 12 and the mold 42 during the feeding cycle reference is briefly made to FIGS. 35. As will be seen, at the outset the stream 12 and the mold 42 are in axial alignment. After a relatively small pool has accumulated in the mold, its lateral travel is initiated and the stream 12 is intercepted by the pool adjacent its border with the cavity defining wall surface of the mold. This relationship between the mold and stream is maintained through the control exercised by cam 65 until the quantity of glass necessary for producing an article, as illustrated for example in FIG. 5, has been accumulated and spinning of the mold is initiated.

Operation The push button 93 is momentarily depressed to effect the energization of solenoid 67 and the relay 89. When solenoid 67 is energized the effect of spring 62 is overcome and arm 61 moves away from the actuator of the servo valve 55, which thereupon permits fluid to flow through conduit 51 to the rightward end of cylinder 50, enabling it to move the carriage 40 leftward to bring the mold 42 axially aligned under the feeder outlet 13. This occurs when cam 65 comes in contact with a roller on arm 61, which is moved by the cam to the position shown and at which time the supply of fluid to cylinder 50 is discontinued.

The feeding cycle is initiated by the momentary depression of a push button 100 which closes contacts 101 to complete the circuits for timer motor 82 and for the associated locking relay 102. As will be evident, since the relay 102 at its contacts 103 completes a locking circuit for itself and an alternative operating circuit for motor $2 through such contacts and through cam contacts 104 these circuits are maintained until contacts 104 are opened.

Cam 1, at its contacts 99 closes a circuit through the winding 24 of magnetic valve for a sufficient time period to effect the operation of shear blades 13 and 14 to sever the stream 12.

Cam 2, at its contacts 165, next closes a circuit for the winding 106 of distributing valve 32 which operates to thereafter supply fluid to the upper end of cylinder 31 to withdraw chute 30 from the path of stream 12, thus permitting charging of the mold 42.

Cam 3 next becomes effective to, at its contacts 113, complete circuits for spinner timer motor and for a lock-up relay 114 via a conductor 115. Relay 1M, upon energizing, at its contacts 116 completes a locking circuit for itself and an alternative operating circuit for motor 45 including contacts 117 of a cam 118.

Cam 4 next becomes effective to, at its contacts 80, close the previously traced circuits of motor 70 and of locking relay 76, thus efltecting rotation of cam 65.

As previously indicated, the cam 65 rotates through an arc of 180 to actuate the servo valve 55 to measurably feed or program the feeding of operating fluid through conduit 52 to cylinder as required for it to move the carriage 40 at the necessary rate for directing the stream 12 into the mold in the previously defined fashion. As the cam 65 completes 180 of rotation cam 86, at contacts 85, interrupts the circuits of solenoid 67 and of the locking relay 89, permitting them to restore.

At substantially the same time cam 5, at its contacts 120, effects the energization of the valve magnet 24 to again operate shear blades 14 and 15 to sever the mold charge from the parent stream of glass. Operation of the shear blades is closely followed by the closure of contacts 122 of cam 6 to again project the chute 32 into the path of stream 12 to divert the oncoming stream from the mold. Upon the de-energization of solenoid 67 spring 62 becomes effective to force the arm 61 into such operative relation with the servo valve 55 as to cause it to unrestrictedly feed fluid to the leftward end of cylinder 50 to move the carriage 40 onto the mold unloading position in which it is shown by full lines.

As previously pointed out, earn 3 starts the operation of spinner timer motor 45, and before cam 65 starts permitting the lateral movement of carriage 40, cam contacts 125 of the spinner timer, as diagrammatically illustrated, effects the closure of the high speed operating circuit of the mold spinning motor 41. At the end of the forming cycle cam contacts close to afford low speed operation of the mold while cooling of the article is being effected.

The rotation of the timer shaft 95 and cam shaft 74 is discontinued in the same fashion as is the shaft 81, as already described.

Aithough the stream 12 may be of constant volume, it is the usual practice to lower a valving needle into the forehearth outlet at the termination of a feeding cycle to substantially restrict the flow of glass between cycles and to raise such needle just before commencement of a feeding cycle to restore the desired rate of flow while feeding a charge. Such operations of the needle can, of course, be readily placed under control of an additional cam on timer shaft 81.

What is claimed is:

1. Apparatus for centrifugally forming articles from molten material which comprises, a carriage laterally movable between two end positions, an open topped ogiveshaped mold arranged on said carriage, means on said carriage for rotating said mold about a vertical axis, means for initially loading molten material into the axial center of said mold when said mold is in one of said end positions, and means for regulating the rate of lateral movement of said carriage and the mold carried thereby while such mold is being loaded so that the molten material is continuously delivered to the surface of the initial axiallyloaded accumulation adjacent the cavity-defining Wall surface of the mold as the mold is loaded to the desired depth.

2. Apparatus for centrifugally forming articles from molten glass-like materials which comprises, a mold carriage, fluid actuated means for linearly moving said carriage along a desired path, an open topped mold having an ogive-shaped cavity rotatably mounted on said carriage, means carried by said carriage for rotating said mold, means for stream feeding molten glass-like material into said mold cavity, said mold carriage being movable along said path to initially position said mold cavity beneath said stream feeding means to initially receive a stream of molten glass-like material in the axial center thereof, and cam actuated means for controlling the flow of fluid to said fluid actuated carriage moving means and program the linear movement of said mold relative to said stream of molten material during loading so that the stream is continuously received by the surface of a pool formed by the initial axial delivery immediately adjacent the cavity-defining walls.

3. In an article centrifuging apparatus, a mold support, an open topped ogive-shaped mold arranged on said support, means for rotating said mold about a vertical axis, a container of molten material having an outlet arranged over said mold for initially issuing a stream of molten material into the axial center thereof, means for effecting relative lateral movement between the mold and said container While a stream is issuing therefrom into said mold, and means for so programming such relative lateral movement as to continuously intercept the stream in an initial accumulation of the material in the mold immediately adjacent the surrounding cavity-defining wall surface of the mold as the mold is filled to a desired depth.

4. A method of centrifugally casting ogive-shaped articles and the like from thermoplastic materials which comprises, initially directing a stream of molten thermoplastic material into the axial center of a casting mold to form an initial accumulation therein, relatively moving such mold laterally with respect to the stream so as to continuously receive the stream in the initial accumulation adjacent the cavity Wall until a desired level of the molten material is obtained in the mold, terminating the delivery of such material to the mold cavity and the lateral movement of the mold, and then centrifugally rotating the mold about a vertical axis to form an article therein.

5. An improved method of centrifugally forming ogive and the like shaped articles from thermoplastic material which comprises, initially delivering a freely falling stream of low viscosity thermoplastic liquid into the axial center of a casting mold, forming an initial accumulation of such thermoplastic liquid in the bottom of such casting mold, moving such mold laterally with respect to such freely falling stream at a variable rate such that the stream is continuously directed into the surface of the initial accumulation adjacent the mold cavity wall until a desired level is obtained, terminating the lateral movement of the mold and the stream feeding of such material thereto, and then centrifugally rotating the mold about a vertical axis passing through its axial center to form an article therein.

References Cited in the tile of this patent UNITED STATES PATENTS 1,174,173 Manning May 7, 1916 1,178,678 Proeger Apr. 11, 1916 1,190,145 Gift July 4, 1916 1,527,729 Dunajefif Feb. 24, 1925 1,607,475 Otto Nov. 16, 1926 1,637,458 Schoonenberg Aug. 2, 1927 1,638,593 Mulholland Aug. 9, 1927 1,751,766 Smith Mar. 25, 1930 2,123,937 Engels July 19, 1938 2,556,237 Teichmann June 12, 1951 2,662,346 Giften Dec. 15, 1953 2,699,013 Hopkins et al. Jan. 11, 1955 2,778,162 Giffen Jan. 22, 1957 2,836,934 McLaughlin June 3, 1958 2,926,457 Trudeau Mar. 1, 1960 2,926,459 Pinotti Mar. 1, 1960 2,970,405 Giffen Feb. 7, 1961 

4. A METHOD OF CENTRIFUGALLY CASTING OGIVE-SHAPED ARTICLES AND THE LIKE FROM THERMOPLASTIC MATERIALS WHICH COMPRISES, INITIALLY DIRECTING A STREAM OF MOLTEN THERMOPLASTIC MATERIAL INTO THE AXIAL CENTER OF A CASTING MOLD TO FORM AN INITIAL ACCUMULATION THEREIN, RELATIVELY MOVING SUCH MOLD LATERALLY WITH RESPECT TO THE STREAM SO AS TO CONTINUOUSLY RECEIVE THE STREAM IN THE INITIAL ACCUMULATION ADJACENT THE CAVITY WALL UNTIL A DESIRED LEVEL OF THE MOLTEN MATERIAL IS OBTAINED IN THE MOLD, TERMINATING THE DELIVERY OF SUCH MATERIAL TO THE MOLD CAVITY AND THE LATERAL MOVEMENT OF THE MOLD, AND THEN CENTRIFUGALLY ROTATING THE MOLD ABOUT A VERTICAL AXIS TO FORM AN ARTICLE THEREIN. 